Damaging torques can be imposed on turboalternators by severe system disturbances. These can result in oscillations in the line of shafts having sufficient amplitude to cause mechanical fatigue, and since fatigue is cumulative, it is essential to keep track of the damage suffered in various zones of the line of shafts.
One such a system is described in the article about a line of shafts entitled "Torsional Monitor Equipment For Turbo-Generator Units" in the American journal "Proceedings of the American Power Conference, 1979, vol. 41, pp. 1163 to 1169". This system includes a device for measuring the opposing torque, which device is in the form of a current transformer and a voltage transformer applying output signals to an analog computer.
However, such special transformers are expensive since they are required to pass very high currents without distortion, and furthermore, they provide inaccurate measurements since they are incapable of taking account of non-linear phenomena between the rotor and the stator of the alternator.
The monitoring system of the present invention uses less expensive means and can provide a more accurate result.